Extend Decode with tuples, lists and bigints

- Reorder tags according to the order in the Erlang manual
  http://erlang.org/doc/apps/erts/erl_ext_dist.html.
- Rename decodefloat to decodenewfloat due to its misleading naming.
Fix Int64 <-> Int errors on 32-bit architectures

- Size unpacking (unsigned, big-endian integers) were broken on 32-bit
  systems due to fixed Int64 specifiers.
- Converting size values to Uint64 seems to solve this issue.
- Even if Erlang supports only 4-bytes wide size values, in some cases
  we need to track larger lengths.  Therefore Uint64 may seem a good
  choice for tracking sizes.
Merge pull request #2 from gbence/decode_features

Extend Decode with tuples, lists and bigints